Light control system

ABSTRACT

A lighting system comprising a lamp arranged to transform electricity into a light beam having properties such as intensity, colour, colour temperature, direction and beam cone angle; a light control means arranged to adjust said light beam properties; an ultrasonic transmitter arranged to transmit ultrasonic signals; an ultrasonic receiver arranged to receive reflected ultrasonic signals; wherein said ultrasonic transmitter and/or receiver are mounted on a rotatable carrier, wherein driving means are present to rotate said carrier; and a processing means arranged to send an ultrasonic pulse repeatedly through said transmitter during rotation at a multitude of angular positions of said carrier and to determine after each pulse is sent if said receiver receives a reflected ultrasonic signal with an amplitude exceeding a predetermined threshold within a predetermined period, and to send control signals to said light control means in dependence of said determination.

CROSS REFERENCE TO RELATED APPLICATION

This application is the 35 U.S.C. §371 national stage of PCT applicationPCT/CN2007/003165, filed Nov. 8, 2007, the disclosure of which is herebyincorporated by reference.

FIELD OF THE INVENTION

The invention relates to a lighting system comprising a lamp arranged totransform electricity into a light beam having properties such asintensity, colour, colour temperature, direction and beam cone angle,and a light control means arranged to adjust said light beam properties.

BACKGROUND OF THE INVENTION

Adjustment of a lamp's properties is well known to be achieved via aremote control (RC). A disadvantage of a remote control is the necessityof the presence of the remote control on the right location at a randommoment. Also a lot of different remote controls are already present inthe living room for TV, audio, VCR, CD/DVD player/recorder, etc.Further, the different buttons on a remote control can be confusing tothe user. Finally, the costs of a remote control and the accompanyingreceiver are relatively high.

Also control of electrical devices by the use of video cameras andmovement detection software is known, wherein the user can control theelectrical device by making gestures in front of the camera. Suchsystems require heavy duty processing power, have a relatively longresponse time, and are relatively expensive.

WO 2006/056814 describes a lighting system comprising a lamp and acontrol means comprising an infrared transmitter, an infrared receiverand a lens arrangement. The control means measure the intensity of thereflected infrared light, and changes the lamp brightness in reactionthereto. In this manner the lamp can be switched on and off, and can bedimmed by hand movements in the infrared beam. Such an arrangement ishowever relatively expensive and inaccurate, as the intensity of thereflected infrared signal heavily depends on the kind of object that ismoved in the beam.

It is a goal of the invention to provide an improved, cheap, reliableand/or easy-to-use control system for lighting. A further goal of theinvention is to provide a lighting system that is safe and comfortablefor its users and their environment.

In existing lighting applications often a very wide illumination of thewhole room is performed. But in many cases only a small part of the roomneeds to be illuminated, which is not energy efficient. Furthermore, inexisting light applications lightbeam focussing and lightbeam positiondeviation is achieved in a mechanical way, which is not flexible and isvulnerable to mechanical failures.

It is a further goal of the invention to provide a more robust, energyefficient, easy to use and/or flexible lighting system.

SUMMARY OF THE INVENTION

According to one aspect of the invention the lighting system furthercomprises a plurality of ultrasonic transmitters arranged to transmitultrasonic signals; a plurality of ultrasonic receivers arranged toreceive reflected ultrasonic signals; and a processing means arranged tosend an ultrasonic pulse sequentially through each of said transmittersand to determine after each pulse is sent which ones of said receiversreceive a reflected ultrasonic signal with an amplitude exceeding apredetermined threshold within a predetermined period, and to sendcontrol signals to said light control means in dependence of saiddetermination. Preferably said ultrasonic transmitters are arranged suchthat the ultrasonic signals are transmitted within and parallel to thelight beam of the lamp. Said ultrasonic transmitters and receivers arepreferably arranged in an equilateral polygon or a circle. In thepreferred embodiment said system comprises three of said transmittersand three of said receivers.

According to another aspect of the invention the lighting system furthercomprises an ultrasonic transmitter arranged to transmit ultrasonicsignals; an ultrasonic receiver arranged to receive reflected ultrasonicsignals; wherein said ultrasonic transmitter and/or receiver are mountedon a rotatable carrier such that the beam of said transmitter and/or thereception cone of said receiver extend parallel to and at a distancefrom the axis of rotation, wherein driving means are present to rotatesaid carrier; and a processing means arranged to send an ultrasonicpulse repeatedly through said transmitter during rotation at a multitudeof angular positions of said carrier and to determine after each pulseis sent if said receiver receives a reflected ultrasonic signal with anamplitude exceeding a predetermined threshold within a predeterminedperiod, and to send control signals to said light control means independence of said determination. Preferably the axis of rotation ofsaid rotatable carrier extends within, and parallel to, the light beamof the lamp. Said processing means is preferably arranged to send anultrasonic pulse at least 3, preferably at least 6, more preferably atleast 12 angular positions of said carrier.

The processing means is in the preferred embodiments of bothaforementioned aspects of the invention further arranged to derive atime-of-flight signal representing the time differences between saidtransmitted and received ultrasonic signals and to send control signalsto said light control means in dependence of said time-of-flight signal,as will be further explained below. This control mechanism provides ahigh resolution control, and is for instance very suitable forcontrolling light intensity, colour and/or colour temperature.

According to a further aspect of the invention the lighting systemfurther comprises at least one ultrasonic transmitter arranged totransmit ultrasonic signals; a plurality of spaced apart ultrasonicreceivers arranged to receive reflected ultrasonic signals; and aprocessing means arranged to determine for each of said receiverstime-of-flight signals representing the time differences between saidtransmitted signals from said at least one transmitter and theassociated received reflected ultrasonic signals from said receiver, andto send control signals to said light control means in dependence of thecombination of said time-of-flight signals for each of said receivers.Preferably said combination of said time-of-flight signals for each ofsaid receivers is a function of said time-of-flight signals defining thelocation of an object reflecting said ultrasonic signals in atwo-dimensional plane or a three-dimensional space within the beams ofsaid transmitters and receivers.

All of the above-mentioned aspects of the invention provide, in a veryefficient, cheap and reliable manner, the possibility to control thelight system by hand gestures in directions substantially perpendicularto the axis of the ultrasound beam(s). If a reflecting object (such as ahand) is present in the beam, the position of the object in saiddirections can continuously be determined, and control of the variousproperties of the lighting system can be achieved thereby.

This control mechanism is suited for switching purposes, for instancefor switching from controlling one light property to another lightproperty. The processing means is therefore in the preferred embodimentsof all three aforementioned aspects of the invention further arranged toselect in dependence of said determination a type of control signalsfrom a plurality of types of control signals, wherein each type ofcontrol signals controls a different one of said light properties.

Another suitable, intuitive purpose of this mechanism is control of thewidth of the light beam angle or of the light beam direction. A user canmove a hand in the beam in a perpendicular direction in order to movethe direction of the light beam or in order to widen or narrow the lightbeam.

Said processing means is preferably arranged to analyse the dynamicbehaviour of said time-of-flight signals and to send control signals tosaid light control means in dependence of said dynamic behaviour.

Said transmitter and receiver are in the aforementioned aspects of theinvention preferably a combined transceiver, and preferably saidtransceiver is provided with a sound horn for narrowing the angle of thesent ultrasonic waves and narrowing the angle of receipt of reflectedsignals.

In a preferred embodiment the lighting system comprises a plurality oflight units, wherein said light units are arranged in at least twogroups forming concentric polygons or circles, wherein the lightbeams ofsubstantially each pair of adjacent light units overlap each other,wherein the lightbeams of the inner group are directed substantiallyparallel to each other, wherein the lightbeams of the light units in theouter group diverge from the lightbeams of the light units in the innergroup, and wherein the light system comprises a light control meanswhich is arranged to adjust the intensity of each one of said pluralityof light units individually.

With the invention two effects can be achieved without physically movingthe lighting system: the direction of the combined light beam of thelight units can be changed, and the angle of the combined light beam canbe changed. Also combinations of these two effects, as well as theseeffects in multiple combined light beams in one lighting system (i.e. inone lamp) can be achieved.

In another preferred embodiment the lighting system comprises aplurality of light units, wherein said light units are arranged in anarray, wherein the lightbeams of substantially each pair of adjacentlight units overlap each other, and wherein the light system comprises alight control means which is arranged to adjust the intensity of eachone of said plurality of light units individually, wherein said lightcontrol means is further arranged to maintain the total combinedluminous flux incident of said plurality of light units on a predefinedimaginary flat surface substantially equal when adapting the intensityof the individual light units. Thereby a smooth transition is obtained,which is very close to the effect that is experienced by a user when alightbeam is moved by physically moving the spotlight, or when the angleof the lightbeam of a spotlight would be changed by physically moving alens. Moreover, the system is arranged thereby to provide a constantoverall brightness experience to a user, independent of the angle withwhich the light beam strikes a surface (for instance a table or afloor).

Said light control means is preferably arranged to adapt the intensityof the individual light units by dimming and/or brightening such thatthe diameter of the combined light beam of the light units that areswitched on increases or decreases smoothly. Thus, preferably the lightunits are not switched on and off suddenly.

Likewise, said light control means is furthermore preferably arranged toadapt the intensity of the individual light units by dimming andbrightening such that the direction of the combined light beam of thelight units that are switched on moves smoothly from a first directionto a second direction.

In the preferred embodiments of the aforementioned two aspects of theinvention said light units are LEDs.

In the preferred embodiments the lighting system furthermore comprises alens extending in the light beam of the light units of said inner groupfor focussing said light beam.

Furthermore in the preferred embodiments the lighting system comprisesat least one middle group of light units extending in a concentricpolygon or circle between the inner and outer groups. The light beams ofsaid middle group are preferably directed substantially parallel to thelight beams of said inner group.

In the preferred embodiments said plurality of light units are containedin one lamp housing, preferably comprising a standard lamp fitting.

The lighting system further preferably comprises at least one ultrasonictransmitter for adapting the light intensity of said individual lightunits by using time-of-flight measurements in the Z-direction (being thelamp axis), as described herein, and/or by using one of the proposalsfor gesture control in the XY-plane (being the plane perpendicular tothe lamp axis) as described herein. In particular gesture control in theXY-plane is well suited for control of the light beam direction and/orangle of the lighting system.

In the preferred embodiments the lighting system comprises an ultrasonictransmitter arranged to transmit ultrasonic signals, an ultrasonicreceiver arranged to receive reflected ultrasonic signals, and aprocessing means arranged to derive a time-of-flight signal representingthe time differences between said transmitted and received ultrasonicsignals and to send control signals, for instance binary code, to saidlight control means in dependence of said time-of-flight signal. Therebya user of the system can adjust the lamp properties by moving an object,such as his hand, in the direction of the axis of the ultrasonic beam.

The ultrasonic transmitters may for instance emit sound at a frequencyof 40 kHz. Although alternatives to the use of ultrasonictransmitters/receivers, such as for instance infrared or radartransmitters/receivers would be capable of measuring the time-of-flightof the respective signals, ultrasound is in particular suitable for thepresent application, since the time-of-flight (where the typicaldistance is between 0.2 and 2 meter) can be measured in millisecondsrather than in nanoseconds, which allows for easy and accuratemeasurement with low cost processing equipment. The system of theinvention can be produced at very low cost, since piezoelectric acoustictransceivers are very cheap.

The system of the invention is easy to control, with a simple userinterface which does not require additional equipment such as a remotecontrol. Other qualities of the system of the invention are itsrobustness, its independency from environmental conditions, itsone-dimensional recognition of control movements, and its low processingpower requirements. The further advantage of an ultrasound sensor isthat it is less influenced by changing ambient light, temperature andhumidity conditions.

Said ultrasonic transmitter and receiver, processing means, and/or lightcontrol means, preferably extend in the lamp housing, and saidultrasonic transmitter and receiver preferably are a combined ultrasonictransceiver. Thereby a compact and easy to install lighting system isprovided, that is intuitively controlled by moving one's hand in thecentre of the light beam. The invention also relates to a single lampunit comprising the entire lighting system as described above.

It is desirable that the ultrasound controlled lighting system is easyto produce in mass quantities, with low cost components, and has smalldimensions so that it can be built-in in even in a small lamp.

In a preferred embodiment the lighting system in accordance with theinvention comprises a LED driver and a pulse width modulator arranged toadjust said light beam properties; a DA-converter, an ultrasound driverand an ultrasonic transmitter arranged to convert a digital transmitsignal into the transmission of an ultrasonic pulse; an ultrasonicreceiver and an amplifier arranged to receive reflected ultrasonicsignals and transform said ultrasonic signal in a voltage, and acomparator arranged to generate a digital receive signal if said voltageis greater than a predetermined threshold; a processing means arrangedto derive a time-of-flight signal representing the time differencesbetween said digital transmit and receive signals and to send controlsignals to said light control means in dependence of said time-of-flightsignal. Preferably said processing means, said pulse width modulator,said DA-converter and said comparator are integrated in a singlemicrocontroller chip. Said microcontroller chip is preferably chosenfrom the single-chip 8-bit 8051/80051 microcontroller family, preferablycomprising small sized RAM and ROM, preferably smaller than 4 kB ROM andsmaller than 512 B RAM.

Preferably said ultrasonic transmitter and said ultrasonic receiver areintegrated in a piezoelectric ultrasound transceiver.

Preferably said transmitting ultrasound driver and said receivingultrasound amplifier are integrated in a pre-processing circuit. Saidpre-processing circuit preferably further comprises a second orderfilter for filtering out low frequent signals from said received signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further explained by means of a preferredembodiment as shown in the accompanying drawings, wherein:

FIG. 1 is a graph showing the principle of time-of-flight measurementwith an ultrasonic transceiver;

FIG. 2 is a schematic perspective view of a lamp and its controlmechanism;

FIG. 3 is a combined drawing showing stills of hand movements in thesystem of FIG. 2 and a graph showing the time-of-flight signal againsttime, and various stages of lamp property control caused by said handmovements;

FIG. 4 is a schematic perspective view of the lamp of FIG. 2;

FIG. 5 is a schematic top view of an average hand;

FIG. 6 is a three-dimensional graph showing beam radius against beamangle and vertical distance;

FIG. 7 shows schematically the movement of a hand in and out of the beamand the related graph of the time-of-flight against time;

FIG. 8 is a schematic cross-sectional view of an ultrasonic transceiverand a horn;

FIGS. 9 and 10 schematically show an electronic hardware implementationof the invention;

FIG. 11 is a perspective view of a lamp according to the invention;

FIG. 12 is a schematic top view of a first and third embodiment of asystem for determining the movement of a hand in a plane by usingultrasonic pulses;

FIG. 13 is a time diagram showing the echoes of ultrasonic pulses in thesystem of FIG. 12;

FIGS. 14A-14H schematically show the movement of a hand in the system ofFIG. 12;

FIG. 15 shows a perspective view of a lamp according to a secondembodiment of a system for determining the movement of a hand in a planeby using ultrasonic pulses;

FIG. 16 shows a schematic front view and a schematic side view of lampof FIG. 15;

FIG. 17 shows a schematic view of the rotation of a ultrasonictransceiver in the lamp of FIG. 15;

FIG. 18 is a time diagram showing the echoes of ultrasonic pulses in thelamp of FIG. 15;

FIGS. 19 and 20 are schematic views of a third embodiment of a systemfor determining the movement of a hand in a plane by using ultrasonicpulses;

FIGS. 21A and 21B/C schematically show the focussing and deviationrespectively of a lightbeam of a LED array lamp;

FIG. 22 shows a schematic cross section and a bottom view of a lamp;

FIG. 23 shows a schematic arrangement of the lamp driver for the lamp ofFIG. 22;

FIGS. 24A-24G schematically shows the beam deviation process of the lampof FIG. 22; and

FIGS. 25A-25E schematically shows the beam focussing process of the lampof FIG. 22.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The lamp 1 as shown in FIG. 2 comprises a plurality of LEDs and anultrasonic transceiver built-in in the centre of said plurality of LEDs.Also a processing means for translating the signals of the transceiverinto control signals, and control means to adjust the light propertiesare built-in.

If the ultrasonic transceiver is switched on it will send an acousticsignal. If an object is present the acoustic signal will be reflected atthe object and will be received by the ultrasonic transceiver inside thelamp. The time difference, called the time-of-flight, between sendingand receiving the acoustic signal will be measured. If the distancebetween the object and the lamp 1 is changed another time-of-flightvalue will be measured. The detected movement of the object is aone-dimensional movement (the object must stay in the ultrasound beamcone). The change in time-of-flight will be translated into a change ina digital control signal. This control signal will control theproperties of the light beam, like colour, intensity or colourtemperature, etc.

The object may be the hand 2 of a user. Thus a one-dimensional movementof the hand 2, like up/down or left/right direction (depending on lampposition, horizontal or vertical) can control the light beam properties.

In commercially available pulse echo distance measurement units of thetransmitter-reflector-receiver type (TRR), the most common task is tomeasure the distance to the closest reflecting object. The measured timeis the representative of travelling twice the distance. The returnedsignal follows essentially the same path back to a receiver locatedclose to the transmitter. Transmitting and receiving transceivers arelocated in the same device. The receiver amplifier sends these reflectedsignals (echoes) to the micro-controller which times them to determinehow far away the object is, by using the speed of sound in air.

The time-of-flight of acoustic signals is commonly used as a distancemeasurement method. A time-of-flight measurement, as illustrated in FIG.1 is formed by subtracting the time-of-transmission (T in FIG. 1) of asignal from the measured time-of-receipt (R in FIG. 1). This timedistance information will be transferred into a binary code in themicroprocessor to control the lamp properties.

In FIG. 2 a hand 2 is the obstacle/object and a table 3, floor orceiling is the reference. The ultrasonic transceiver sends an ultrasonicwave in the form of a beam cone 4. If the distance y from thetransceiver to the reference is 1.5 m, the total travel distance for theultra-sound beam 4 is 2*y=3 m. The time-of-flight then is 8.7 ms (at anambient temperature of 25° C.). If the distance x from the transceiverto the hand is 0.5 m, the time-of-flight is 2.9 ms. If the requiredaccuracy of control steps of the hand movement is 2 cm (time-of-flightsteps of 0.12 ms), and the range of control is for instance 64 cm, thereare 32 control steps, which allows for 5-bit control.

The control signal as shown in FIG. 3 is made by the movement of thehand 2 in a one-dimensional vertical direction in the ultrasonic beam 4.At T1=1 s the hand 2 is outside the beam, the reference value ismeasured, and lamp control is disabled (stage A). At T2=2 s the hand 2moves into the beam 4 and is held there for more than 1 second until atT3=3 s lamp control is enabled by the microcontroller (stage B). Thenthe hand 2 moves up between T3=3 s and T5=5 s, whereby for instance theintensity of the lamp 1 is increased by the microprocessor (stage C). AtT6=6 s the hand is withdrawn from the beam 4 so that the reference valueis measured, and lamp control is disabled thereby (stage D). Anaccidental movement of the hand 2 in the ultrasonic beam 4 as shown atT7=7 s does therefore not result in an accidental adjustment of the lampproperties (stage E). Hence, the lamp control is activated by holding anobject in the ultrasonic beam 4 for more than 1 second.

The ultrasonic beam cone angle is important to provide reliable handcontrol. In FIG. 4 the beam radius at the reference position is r. Thebeam radius rh at the hand position must be high enough to have optimumcontrol by hand. During control of a lamp property the average beamradius should be equal to approximately half the length of the averagehand shape as shown in FIG. 5. If the total control range is around X/2(for a lamp/table application), the ultrasound beam angle at the minimumbeam radius during control of the lamp property will be around Lh/2. Forexample: if Lh=150 mm and X=1.5 m, the ultrasound beam angle θ should be11°. The relationship between the vertical distance X and the beam angleas function of the beam radius is shown in FIG. 6. Lamp control will bepossible if the hand 2 is in the narrow ultrasound cone 4 as shown inFIG. 7. Reduction of a wide ultrasound beam 4 and an increase of soundpressure level (SPL) of an ultrasonic transceiver 5 may be achieved by ahorn 6 as shown in FIG. 8.

In order to reduce the costs of the lamp to a minimum and to have thepossibility to control all possible lighting parameters like colour,intensity, etcetera, the electronic circuit needed for carrying out thecontrol functions is integrated in the lamp. The microprocessor used forgesture control is also integrated in the LED control microprocessor toreduce the cost even more. The integration of the ultrasound sensor inthe lamp makes low cost, high volume production possible.

With reference to FIG. 9, as explained above the micro-controller sendsa pulse to the ultrasound transmitter of the ultrasound transceiver 5. Adigital pulse signal is generated by the control part 13A of amicro-controller 13, and converted by DA-converter 17 in saidmicro-controller 13 into an electric pulse. This pulse will be amplifiedby the amplifier 18 in the pre-processor 10 (shown in more detail inFIG. 10) to a value that can be used by the ultrasound transmitter partof the ultrasound transceiver 5. Then the piezo-electric ultrasoundtransceiver 5 sends an acoustic signal (for instance at a frequency of40 kHz). An object will reflect this acoustic signal. The pre-processor10 will receive the reflected signal via the ultrasound transceiver 5.In order to reduce the influence of outside disturbances the signal isfiltered by a 2nd order High-Pass filter 11 of for instance 20 kHz(=fc). After filtering the signal is amplified by amplifier 12 in thepre-processor 10.

Microcontroller 13 comprises a comparator 14, which creates a digitalpulse signal from the electric signal received from the pre-processor10, which can be processed by the micro-controller 13.

The micro-controller 13 further comprises a LED driver part 13B, with amodulator 20, which is connected to the LED driver 19, and part of theROM 15 and the RAM 16, which is shared, with the control part 13A of themicro-controller.

Such a micro-controller 13, arranged to drive a LED, is well known inthe art, but is further programmed to perform the control functions asdescribed above. The micro-controller can be a simple processor, forinstance of the 8051-family. The size of the ROM 15 can be as low as 2kB and the size of the RAM 16 can be as low as 256 bytes.

FIG. 11 shows a lamp according to the invention comprising a housingwith a standard incandescent lamp type fitting, ten LEDs 21 arranged ina circle, a transceiver 5 in a horn 6. All the electronic componentslike the micro-controller 13, pre-processor 10 and LED driver 19 arebuilt-in in the housing 23. Thereby a very compact lighting system isobtained, which requires no further external accessories to be operatedand controlled.

Now with reference to FIGS. 12-18 an extended lighting system isdescribed that allows control of light parameters by gesture (e.g. handdisplacement) in a XY-plane, which extends perpendicular to the Z-axis,being the axis of the light beam of the lamp. This will introduceadditional possibilities for gesture light control, which can becombined with the above described method for gesture light control inthe Z-direction based on time-of-flight measurements. For example it ispossible to pull or push the light beam by hand movement in a certaindirection. Also light control is possible for example by hand movementin a circular motion. By using also the time-of-flight determination asdescribed above, a combination of two light controls is possible, likelight beam deviation and light intensity could be controlled at the sametime. Alternatively the gestures in the XY-plane can be used forswitching from controlling one light beam property to another light beamproperty.

A first embodiment is described with reference to FIGS. 12-14. Accordingto FIG. 12 the lamp 1 is provided with three piezoelectric ultrasoundtransceivers 5 mounted in a triangular shape, which are arranged suchthat the axes of their ultrasound beams extend parallel to the axis ofthe light beam 4 and in said light beam 4. The position of an object,such as the hand 2 in the XY-plane, is determined by object detection bysaid three transceivers 5. Said position is determined by sequentiallytransmitting an acoustic pulse from one transceiver 5 at a time. Each ofthe three transceivers 5 determines if a reflected signal is receivedafter each pulse is sent by one of said transceivers 5.

The object position determined by this sequential transmitting andparallel receiving method is translated into a binary code. From thiscode the XY-position of the object is determined, and is translated intolight control instructions, like light beam deviation or other lightcontrols like colour, intensity, focus, etcetera.

In FIG. 13 a time diagram is given of the proposed method. The threetransceivers subsequently send acoustic signals on three time intervalst0, t1 and t2. The three transceivers will determine if an echo signalsent by a transmitter is received, which depends on the position of thehand 2. In FIG. 13 a dotted block indicates that the received echosignal strength is below a predetermined threshold and the echo signalis given value 0. If the echo signal strength is equal to or above saidthreshold the echo signal is given the value 1. This echo information isrepresented in table 1.

TABLE 1 example of information of sequential transmitting and parallelreceiving method Sequential Transmitting Parallel Receiving Time T1 T2T3 R1 R2 R3 t = t₀ T1₀ = 1 T2₀ = 0 T3₀ = 0 R1₀ = 1 R2₀ = 0 R3₀ = 1 t =t₁ T1₁ = 0 T2₁ = 1 T3₁ = 0 R1₁ = 1 R2₁ = 0 R3₁ = 0 t = t₂ T1₂ = 0 T2₂ =0 T3₂ = 1 R1₂ = 1 R2₂ = 0 R3₂ = 0

This binary information is translated into a position in the XY-plane byfollowing equations:

$\begin{matrix}{x = {\sum\limits_{p = 0}^{n - 1}{\left( T_{p + 1} \right)_{p} \cdot \left\lbrack {\sum\limits_{k = 0}^{n - 1}{\left( R_{k + 1} \right)_{p} \cdot \left( {Wx}_{k + 1} \right)_{p}}} \right\rbrack}}} \\{y = {\sum\limits_{q = 0}^{n - 1}{\left( T_{q + 1} \right)_{q} \cdot \left\lbrack {\sum\limits_{m = 0}^{n - 1}{\left( R_{m + 1} \right)_{q} \cdot \left( {Wy}_{m + 1} \right)_{q}}} \right\rbrack}}}\end{matrix}$

Where n is the total number of transceivers

1. Wx and Wy are weight factors

2. k and m are transceiver indices

The X and Y value determine the actual position of the hand 2 in theXY-plane. If the hand 2 is moving to a certain direction the X, Y valueschange. From these values the hand displacement direction is known.

If the hand 2 moves outside the control range in the X or Y direction orboth, the values are fixed to a constant value. The movement directionand distance of the hand 2 and/or its actual position will be translatedinto a light control instruction, e.g. a deflection action of the lightbeam in a certain XY direction.

A hand generally has a spherical shape, which causes beam scatteringeffects. To reduce the influence of scattering on the measurement resulthorns of e.g. 10 degrees beam angle are preferably placed on thetransceivers. An extra advantage for using a 10 degrees horn is a highersound pressure level of the sent signals.

The above method provides at least four/five valid steps in eachdirection. The calculated XY-positions are translated into a lightcontrol value in the user interface.

As an example a sequence of hand movements comprising 8 steps is shownin FIGS. 14A-14H, and for each step a table with transmitted andreceived binary values for each transceiver is shown below, with thecalculated values for X and Y.

TABLE 2a (FIG. 14A, step 1): X = 0, Y = −0.5 Sequential TransmittingParallel Receiving Time T1 T2 T3 R1 R2 R3 t = t₀ T1₀ = 1 T2₀ = 0 T3₀ = 0R1₀ = 1 R2₀ = 1 R3₀ = 1 t = t₁ T1₁ = 0 T2₁ = 1 T3₁ = 0 R1₁ = 1 R2₁ = 1R3₁ = 1 t = t₂ T1₂ = 0 T2₂ = 0 T3₂ = 1 R1₂ = 1 R2₂ = 1 R3₂ = 1

TABLE 2b (FIG. 14B, step 2): X = −0.5, Y = −0.5 Sequential TransmittingParallel Receiving Time T1 T2 T3 R1 R2 R3 t = t₀ T1₀ = 1 T2₀ = 0 T3₀ = 0R1₀ = 1 R2₀ = 0 R3₀ = 1 t = t₁ T1₁ = 0 T2₁ = 1 T3₁ = 0 R1₁ = 0 R2₁ = 0R3₁ = 0 t = t₂ T1₂ = 0 T2₂ = 0 T3₂ = 1 R1₂ = 1 R2₂ = 0 R3₂ = 0

TABLE 2c (FIG. 14C, step 3): X = −1, Y = −0.5 Sequential TransmittingParallel Receiving Time T1 T2 T3 R1 R2 R3 t = t₀ T1₀ = 1 T2₀ = 0 T3₀ = 0R1₀ = 1 R2₀ = 0 R3₀ = 0 t = t₁ T1₁ = 0 T2₁ = 1 T3₁ = 0 R1₁ = 0 R2₁ = 0R3₁ = 0 t = t₂ T1₂ = 0 T2₂ = 0 T3₂ = 1 R1₂ = 0 R2₂ = 0 R3₂ = 0

TABLE 2d (FIG. 14D, step 4): object outside range X, Y not changedSequential Transmitting Parallel Receiving Time T1 T2 T3 R1 R2 R3 t = t₀T1₀ = 1 T2₀ = 0 T3₀ = 0 R1₀ = 0 R2₀ = 0 R3₀ = 0 t = t₁ T1₁ = 0 T2₁ = 1T3₁ = 0 R1₁ = 0 R2₁ = 0 R3₁ = 0 t = t₂ T1₂ = 0 T2₂ = 0 T3₂ = 1 R1₂ = 0R2₂ = 0 R3₂ = 0

TABLE 2e (FIG. 14E, step 5): X = 0, Y = −0.5 Sequential TransmittingParallel Receiving Time T1 T2 T3 R1 R2 R3 t = t₀ T1₀ = 1 T2₀ = 0 T3₀ = 0R1₀ = 1 R2₀ = 1 R3₀ = 1 t = t₁ T1₁ = 0 T2₁ = 1 T3₁ = 0 R1₁ = 1 R2₁ = 1R3₁ = 1 t = t₂ T1₂ = 0 T2₂ = 0 T3₂ = 1 R1₂ = 1 R2₂ = 1 R3₂ = 1

TABLE 2f (FIG. 14F, step 6): X = +0.5, Y = −0.5 Sequential TransmittingParallel Receiving Time T1 T2 T3 R1 R2 R3 t = t₀ T1₀ = 1 T2₀ = 0 T3₀ = 0R1₀ = 0 R2₀ = 0 R3₀ = 0 t = t₁ T1₁ = 0 T2₁ = 1 T3₁ = 0 R1₁ = 0 R2₁ = 1R3₁ = 1 t = t₂ T1₂ = 0 T2₂ = 0 T3₂ = 1 R1₂ = 0 R2₂ = 1 R3₂ = 0

TABLE 2g (FIG. 14G, step 7): X = +1, Y = −0.5 Sequential TransmittingParallel Receiving Time T1 T2 T3 R1 R2 R3 t = t₀ T1₀ = 1 T2₀ = 0 T3₀ = 0R1₀ = 0 R2₀ = 0 R3₀ = 0 t = t₁ T1₁ = 0 T2₁ = 1 T3₁ = 0 R1₁ = 0 R2₁ = 1R3₁ = 0 t = t₂ T1₂ = 0 T2₂ = 0 T3₂ = 1 R1₂ = 1 R2₂ = 0 R3₂ = 0

TABLE 2h (FIG. 14H, step 8): object outside range X, Y not changedSequential Transmitting Parallel Receiving Time T1 T2 T3 R1 R2 R3 t = t₀T1₀ = 1 T2₀ = 0 T3₀ = 0 R1₀ = 0 R2₀ = 0 R3₀ = 0 t = t₁ T1₁ = 0 T2₁ = 1T3₁ = 0 R1₁ = 0 R2₁ = 0 R3₁ = 0 t = t₂ T1₂ = 0 T2₂ = 0 T3₂ = 1 R1₂ = 0R2₂ = 0 R3₂ = 0

Now with reference to FIGS. 15-18 an second embodiment for determiningthe hand position in the XY-plane will be described. The method iscomparable with the above described method, but distinguishes itself inthat only one ultrasound transceiver 5 is used, which is rotated in thelamp around the lamp axis, such that object localization can be achievedin one revolution.

According to FIGS. 15 and 16 the lamp 1 comprises an array of LEDs 21and a piezoelectric ultrasound transceiver 5 mounted on a rotatingcogwheel 30, such that the transceiver 5 moves along the circumferenceof the lamp 1. The cogwheel 30 is driven by another small cogwheel 31,which is connected to a stepper motor 32. The transceiver rotation speedis higher than the hand movement in the XY-plane. For example if thetransceiver rotation speed is 4 Hz, then the time needed for onerevolution of the transceiver is 250 ms. Within this period thexy-position of the object is detected, in which period the hand 2 willnot have been moved significantly.

In order to determine the transceiver position along the circumferenceof the lamp, a reference transceiver position is defined by a blockingfilter 33 for ultrasound signals arranged at said position. Thereference calibration to determine said reference position can becarried out in one transceiver revolution. The rotation of thetransceiver 5 will be activated when an object, such as hand 2 is placedin the transceiver detection range.

Said position is determined by transmitting an acoustic pulse from saidtransceiver 5 and determining if a reflected signal is received, andthen rotate said transceiver 5 to the next position and repeat thisstep, until such determination is achieved at twelve positions, as shownin FIG. 17.

In FIG. 18 a time diagram is given of the proposed method. Thetransceiver subsequently sends acoustic signals (T0 . . . T11) on twelvetime intervals t0, t1 . . . t11. At each step the transceiver 5 willdetermine if an echo signal is received (R0 . . . R11), which depends onthe position of the hand 2. In FIG. 18 a dotted block indicates that thereceived echo signal strength is below a predetermined threshold and theecho signal is given value 0. If the echo signal strength is equal to orabove said threshold the echo signal is given the value 1. An example ofthis echo information is shown in table 3.

TABLE 3 Time Transmitter T Receiver R t = t₀ T₀ = 1 R₀ = 1 t = t₁ T₁ = 1R₁ = 1 t = t₂ T₂ = 1 R₂ = 1 t = t₃ T₃ = 1 R₃ = 1 t = t₄ T₄ = 1 R₄ = 0 t= t₅ T₅ = 1 R₅ = 0 t = t₆ T₆ = 1 R₆ = 0 t = t₇ T₇ = 1 R₇ = 0 t = t₈ T₈ =1 R₈ = 0 t = t₉ T₉ = 1 R₉ = 0 t = t₁₀ T₁₀ = 1 R₁₀ = 0 t = t₁₁ T₁₁ = 1R₁₁ = 1

This binary information is translated into a position in the XY-plane bythe following equations:

$\begin{matrix}{x = {\sum\limits_{p = 0}^{n - 1}{T_{p} \cdot R_{p} \cdot {Wx}_{p}}}} \\{y = {\sum\limits_{p = 0}^{n - 1}{T_{p} \cdot R_{p} \cdot {Wy}_{p}}}}\end{matrix}$

Where n is the total number of measurements during

1. one sensor revolution

2. Wx and Wy are weight factors

The weight factor values depends on the transceiver position during themeasurement compared to the reference position.

Now with reference to FIGS. 19-20 a third embodiment for determining thehand position in the XY-plane will be described.

According to FIGS. 19 and 20 the lamp 1 is provided with twopiezoelectric ultrasound transceivers 5, which are arranged such thatthe axes of their ultrasound beams extend parallel to the axis of thelight beam 4 and in said light beam 4. Alternatively, in order toachieve more accurate results, more transceivers can be applied, forinstance three transceivers, which are positioned in a triangle as inFIG. 12. The position of an object, such as the hand 2 in the XY-plane,is determined by determining the time-of-flight by said transceivers 5.Said position is determined by sequentially transmitting an acousticpulse from one transceiver 5 at a time. After each pulse is sent by oneof said transceivers 5, each of the transceivers 5 determines thetime-of-flight of the reflected signal in accordance with the earlierdescribed method. In principle the method needs only one transmitter tosend an acoustic pulse and two receivers to determine the time-of-flightof the reflected signal.

The position of the object is determined by combining the time-of-flightmeasurements of said two or more receivers. In order to achieve reliabledeterminations the distance between the ultrasound sensors must besufficiently high. If for instance the accuracy of a time-of-flightmeasurement is 2 cm, for reliable position determination of an object at1 m from the transceivers the distance between two sensors must be atleast 28 cm. The ultrasound beam angle in this case must be sufficientlyhigh.

Example 1

The number of sensors is two, one transceiver (transmitter & receiver)and one receiver.

The distance in a XY-plane can be calculated as follows:

v _(air)·(TOF _(T1) _(—) _(R1))_(t=t0)=√{square root over ((x ₁ −x₀)²+(y ₁ −y ₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²)}+√{squareroot over ((x ₀ −x ₁)²+(y ₀ −y ₁)²)}{square root over ((x ₀ −x ₁)²+(y ₀−y ₁)²)}=a

v _(air)·(TOF _(T1) _(—) _(R2))_(t=t0)=√{square root over ((x ₁ −x₀)²+(y ₁ −y ₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²)}+√{squareroot over ((x ₀ −x ₂)²+(y ₀ −y ₂)²)}{square root over ((x ₀ −x ₂)²+(y ₀−y ₂)²)}=b

where v_(air)=speed of sound at room temperature, is 344 m/s.

To simplify the calculations the sensors are placed in the XY-plane. Thereceivers are placed so that both are on the X-axis and one on theY-axis. The only parameter that has to be defined for the sensor unitsis the distance d, between the sensors. With these assumptions the newcoordinates for the transmitter and the receivers become:

Receivers: R₁=(0,0)

-   -   i. R₂=(d,0)

Transmitter: T₁=(0,0)

With the new coordinates above-mentioned expression become much easierto handle:

for t=t₀:

$\begin{matrix}{a = \left. {2 \cdot \sqrt{\left( x_{0} \right)^{2} + \left( y_{0} \right)^{2}}}\Rightarrow\sqrt{\left( x_{0} \right)^{2} + \left( y_{0} \right)^{2}} \right.} \\{= \frac{a}{2}} \\{b = {\sqrt{\left( x_{0} \right)^{2} + \left( y_{0} \right)^{2}} + \sqrt{\left( {x_{0} - d} \right)^{2} + \left( y_{0} \right)^{2}}}}\end{matrix}$

The object position x₀,y₀ at t=t₀ will be

$\begin{matrix}{\left( x_{0} \right)_{t = {t\; 0}} = \frac{\left( {\frac{a^{2}}{2} + d^{2} - b^{2} - {a \cdot b}} \right)}{2 \cdot d}} \\{\left( y_{0} \right)_{t = {t\; 0}} = \sqrt{\left( \frac{a}{2} \right)^{2} - \left( \left( x_{0} \right)_{t = {t\; 0}} \right)^{2}}}\end{matrix}$

This position at t=t₀ is used as the initial position of the hand.

The same measurements will be repeated at another time t=t₁ fordetecting movement distance direction of the object.

The movement direction is calculated as follows:

Δx=(x ₀)_(t=t0)−(x ₀)_(t=t1)

Δy=(y ₀)_(t=t0)−(y ₀)_(t=t1)

If Δx is positive then the hand moves in the left direction, if Δy ispositive then the hand moves in the downwards direction. Thus in thiscase the hand moves towards the southwest direction. This positionchange is translated into a binary code and used for controlling thelight beam properties, for instance for deviating the light beam intothe same direction as object moves, towards the southwest direction.

Example 2

In order to be able to determine the displacement of the object in thez-direction an additional transceiver is included. Determination of thedisplacement in the z-direction can be used for additional menu control.In this example one transmitter and three receivers are used, in aconfiguration as in FIG. 12. The basic principle is the same as inexample 1. Time-of-flight measurements are performed on three sensorsnow instead of two: one transceiver and two receivers.

Distance calculation can be performed from the transmitter to the object(hand) and from the object to the three receivers by the followingequations:

v _(air)·(TOF)_(t=t0)=√{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁−z ₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z ₀)²)}{squareroot over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z ₀)²)}+√{square root over ((x₀ −x ₁)²+(y ₀ −y ₁)²+(z ₀ −z ₁)²)}{square root over ((x ₀ −x ₁)²+(y ₀ −y₁)²+(z ₀ −z ₁)²)}{square root over ((x ₀ −x ₁)²+(y ₀ −y ₁)²+(z ₀ −z₁)²)}

v _(air)·(TOF _(T1,R2))_(t=t0)=√{square root over ((x ₁ −x ₀)²+(y ₁ −y₀)²+(z ₁ −z ₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z ₀)²)}+√{squareroot over ((x ₀ −x ₂)²+(y ₀ −y ₂)²+(z ₀ −z ₂)²)}{square root over ((x ₀−x ₂)²+(y ₀ −y ₂)²+(z ₀ −z ₂)²)}{square root over ((x ₀ −x ₂)²+(y ₀ −y₂)²+(z ₀ −z ₂)²)}

v _(air)·(TOF _(T1,R3))_(t=t0)=√{square root over ((x ₁ −x ₀)²+(y ₁ −y₀)²+(z ₁ −z ₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z ₀)²)}+√{squareroot over ((x ₀ −x ₃)²+(y ₀ −y ₃)²+(z ₀ −z ₃)₂)}{square root over ((x ₀−x ₃)²+(y ₀ −y ₃)²+(z ₀ −z ₃)₂)}{square root over ((x ₀ −x ₃)²+(y ₀ −y₃)²+(z ₀ −z ₃)₂)}

These are 3 equations with 3 unknowns. The calculation result is:(x₀)_(t=t0), (y₀)_(t=t0), (z₀)_(t=t0). This is the initial position ofthe object.

These measurements and calculations are repeated at t=t₁ for detectingmovement distance and direction of the object, which will result in(x₀)_(t=t1), (y₀)_(t=t1), (z₀)_(t=t1), etcetera.

Movement direction is calculated as follows:

Δx=(x ₀)_(t=t0)−(x ₀)_(t=t1)

Δy=(y ₀)_(t=t0)−(y ₀)_(t=t1)

Δz=(z _(O))_(t=t0)−(z ₀)_(t=t1)

If Δx is positive then the object moves in the left direction, if Δy ispositive then the object moves in pull direction and if Δz is positivethen the object moves in a downwards direction.

Thus the object moves towards the southwest-downwards direction (in theXYZ-space). This position will be translated into a binary code and usedfor light beam properties control, for instance in this case fordeviating the light beam into the same direction as the object, towardsthe southwest direction. Another example of the use of this positioninformation: the movement in the XY-directions controls the direction ofthe light beam deviation and movement in the Z-direction controls themagnitude of the light beam deviation.

Example 3

In this example a system with three transceivers is described, in aconfiguration as in FIG. 12. This provides the possibility to measurethe object position three times from different transmitter positions.

First at t=t₀ transmitter T1 will send an acoustic signal to the object.The signal will be reflected at the object and will be received by thethree receivers (R1, R2, R3).

v _(air)·(TOF _(T1,R1))_(t=t0)=√{square root over ((x ₁ −x ₀)²+(y ₁ −y₀)²+(z ₁ −z ₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z ₀)²)}+√{squareroot over ((x ₀ −x ₁)²+(y ₀ −y ₁)²+(z ₀ −z ₁)²)}{square root over ((x ₀−x ₁)²+(y ₀ −y ₁)²+(z ₀ −z ₁)²)}{square root over ((x ₀ −x ₁)²+(y ₀ −y₁)²+(z ₀ −z ₁)²)}

v _(air)·(TOF _(T1,R2))_(t=t0)=√{square root over ((x ₁ −x ₀)²+(y ₁ −y₀)²+(z ₁ −z ₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z ₀)²)}+√{squareroot over ((x ₀ −x ₂)²+(y ₀ −y ₂)²+(z ₀ −z ₂)²)}{square root over ((x ₀−x ₂)²+(y ₀ −y ₂)²+(z ₀ −z ₂)²)}{square root over ((x ₀ −x ₂)²+(y ₀ −y₂)²+(z ₀ −z ₂)²)}

v _(air)·(TOF _(T1,R3))_(t=t0)=√{square root over ((x ₁ −x ₀)²+(y ₁ −y₀)²+(z ₁ −z ₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z₀)²)}{square root over ((x ₁ −x ₀)²+(y ₁ −y ₀)²+(z ₁ −z ₀)²)}+√{squareroot over ((x ₀ −x ₃)²+(y ₀ −y ₃)²+(z ₀ −z ₃)²)}{square root over ((x ₀−x ₃)²+(y ₀ −y ₃)²+(z ₀ −z ₃)²)}{square root over ((x ₀ −x ₃)²+(y ₀ −y₃)²+(z ₀ −z ₃)²)}

These are 3 equations with 3 unknowns. The calculation result is[(x₀)_(t=t0)]_(T1), [(y_(O))_(t=t0)]_(T1), [(z_(O))_(t=t0)]₁₁

At t=t₁ transmitter T2 will send an acoustic signal to the object. Thesignal will be reflected at the object and will be received by the threereceivers.

v _(air)·(TOF _(T2,R1))_(t=t1)=√{square root over ((x ₂ −x ₀)²+(y ₂ −y₀)²+(z ₂ −z ₀)²)}{square root over ((x ₂ −x ₀)²+(y ₂ −y ₀)²+(z ₂ −z₀)²)}{square root over ((x ₂ −x ₀)²+(y ₂ −y ₀)²+(z ₂ −z ₀)²)}+√{squareroot over ((x ₀ −x ₁)²+(y ₀ −y ₁)²+(z ₀ −z ₁)²)}{square root over ((x ₀−x ₁)²+(y ₀ −y ₁)²+(z ₀ −z ₁)²)}{square root over ((x ₀ −x ₁)²+(y ₀ −y₁)²+(z ₀ −z ₁)²)}

v _(air)·(TOF _(T2,R2))_(t=t1)=√{square root over ((x ₂ −x ₀)²+(y ₂ −y₀)²+(z ₂ −z ₀)²)}{square root over ((x ₂ −x ₀)²+(y ₂ −y ₀)²+(z ₂ −z₀)²)}{square root over ((x ₂ −x ₀)²+(y ₂ −y ₀)²+(z ₂ −z ₀)²)}+√{squareroot over ((x ₀ −x ₂)²+(y ₀ −y ₂)²+(z ₀ −z ₂)²)}{square root over ((x ₀−x ₂)²+(y ₀ −y ₂)²+(z ₀ −z ₂)²)}{square root over ((x ₀ −x ₂)²+(y ₀ −y₂)²+(z ₀ −z ₂)²)}

v _(air)·(TOF _(T2,R3))_(t=t1)=√{square root over ((x ₂ −x ₀)²+(y ₂ −y₀)²+(z ₂ −z ₀)²)}{square root over ((x ₂ −x ₀)²+(y ₂ −y ₀)²+(z ₂ −z₀)²)}{square root over ((x ₂ −x ₀)²+(y ₂ −y ₀)²+(z ₂ −z ₀)²)}+√{squareroot over ((x ₀ −x ₃)²+(y ₀ −y ₃)²+(z ₀ −z ₃)²)}{square root over ((x ₀−x ₃)²+(y ₀ −y ₃)²+(z ₀ −z ₃)²)}{square root over ((x ₀ −x ₃)²+(y ₀ −y₃)²+(z ₀ −z ₃)²)}

These are 3 equations with 3 unknowns. The calculation result is[(x₀)_(t=t1)]_(T2), [(y_(O))_(t=t1)]_(T2), [(z₀)_(t=t1)]_(T2).

At t=t₂ transmitter T3 will send an acoustic signal to the object. Thesignal will be reflected at the object and will be received by the threereceivers.

v _(air)·(TOF _(T2,R1))_(t=t2)=√{square root over ((x ₃ −x ₀)²+(y ₃ −y₀)²+(z ₃ −z ₀)²)}{square root over ((x ₃ −x ₀)²+(y ₃ −y ₀)²+(z ₃ −z₀)²)}{square root over ((x ₃ −x ₀)²+(y ₃ −y ₀)²+(z ₃ −z ₀)²)}+√{squareroot over ((x ₀ −x ₁)²+(y ₀ −y ₁)²+(z ₀ −z ₁)²)}{square root over ((x ₀−x ₁)²+(y ₀ −y ₁)²+(z ₀ −z ₁)²)}{square root over ((x ₀ −x ₁)²+(y ₀ −y₁)²+(z ₀ −z ₁)²)}

v _(air)·(TOF _(T3,R2))_(t=t2)=√{square root over ((x ₃ −x ₀)²+(y ₃ −y₀)²+(z ₃ −z ₀)²)}{square root over ((x ₃ −x ₀)²+(y ₃ −y ₀)²+(z ₃ −z₀)²)}{square root over ((x ₃ −x ₀)²+(y ₃ −y ₀)²+(z ₃ −z ₀)²)}+√{squareroot over ((x ₀ −x ₂)²+(y ₀ −y ₂)²+(z ₀ −z ₂)²)}{square root over ((x ₀−x ₂)²+(y ₀ −y ₂)²+(z ₀ −z ₂)²)}{square root over ((x ₀ −x ₂)²+(y ₀ −y₂)²+(z ₀ −z ₂)²)}

v _(air)·(TOF _(T3,R3))_(t=t2)=√{square root over ((x ₃ −x ₀)²+(y ₃ −y₀)²+(z ₃ −z ₀)²)}{square root over ((x ₃ −x ₀)²+(y ₃ −y ₀)²+(z ₃ −z₀)²)}{square root over ((x ₃ −x ₀)²+(y ₃ −y ₀)²+(z ₃ −z ₀)²)}+√{squareroot over ((x ₀ −x ₃)²+(y ₀ −y ₃)²+(z ₀ −z ₃)²)}{square root over ((x ₀−x ₃)²+(y ₀ −y ₃)²+(z ₀ −z ₃)²)}{square root over ((x ₀ −x ₃)²+(y ₀ −y₃)²+(z ₀ −z ₃)²)}

These are 3 equations with 3 unknowns. The calculation result is[(x₀)_(t=t2)]_(T3), [(y₀)_(t=t2)]_(T3), [(z₀)_(t=t2)]_(T3).

To have a more reliable position of the object an average of the threemeasurements at t=t₀, t=t₁ and t=t₂ is calculated. This is possiblebecause the sample frequency for object localization is much higher thanthe object movement speed.

$\begin{matrix}{\left( x_{0} \right)_{ta} = \frac{\left\lbrack \left( x_{0} \right)_{t = {t\; 0}} \right\rbrack_{T\; 1} + \left\lbrack \left( x_{0} \right)_{t = {t\; 1}} \right\rbrack_{T\; 2} + \left\lbrack \left( x_{0} \right)_{t = {t\; 2}} \right\rbrack_{T\; 3}}{3}} \\{\left( y_{0} \right)_{ta} = \frac{\left\lbrack \left( y_{0} \right)_{t = {t\; 0}} \right\rbrack_{T\; 1} + \left\lbrack \left( y_{0} \right)_{t = {t\; 1}} \right\rbrack_{T\; 2} + \left\lbrack \left( y_{0} \right)_{t = {t\; 2}} \right\rbrack_{T\; 3}}{3}} \\{\left( z_{0} \right)_{ta} = \frac{\left\lbrack \left( z_{0} \right)_{t = {t\; 0}} \right\rbrack_{T\; 1} + \left\lbrack \left( z_{0} \right)_{t = {t\; 1}} \right\rbrack_{T\; 2} + \left\lbrack \left( z_{0} \right)_{t = {t\; 2}} \right\rbrack_{T\; 3}}{3}}\end{matrix}$

This position is the initial position of the object.

These measurements and calculations will be repeated at t_(b) (t₃, t₄,t₅) for detecting movement and movement direction of the object, whichwill result in (x₀)_(tb), (y₀)_(tb), (z₀)_(tb).

Movement direction will be calculated as follows:

Δx=(x ₀)_(ta)−(x ₀)_(tb)

Δy=(y ₀)_(ta)−(y ₀)_(tb)

Δz=(z ₀)_(ta)−(z ₀)_(tb)

If Δx is positive then the object moves in the left direction, if Δy ispositive then the object moves in pull direction and if Δz is positivethe object moves in a downwards direction.

Thus the object moves towards southwest-downwards direction (in theXYZ-space). This position will be translated into a binary code and usedfor light control purposes, for instance it will deviate the light beaminto the same direction as the object moves, in this case towardssouthwest direction, and at the same time for instance the lightintensity will be decreased. Another example of the use of this positioninformation: the movement in the XY-directions controls the direction ofthe light beam deviation and movement in the Z-direction controls themagnitude of the light beam deviation.

With reference to FIGS. 21-25 a lamp 1 is described which is capable ofcontinuous focus control (FIG. 21) and deflection (FIGS. 21B and 21C) ofa light beam in a wide range as well as in a small region, withoutmoving any physical parts of the lamp 1. This lamp is preferablycombined with the XY-plane gesture control system as described above forchanging the direction or focus of the light beam.

According to FIG. 22 the lamp 1 is divided into three separated ringshaped parts 40A, 40B, 40C, each comprising an array of LEDs 21. SaidLEDs may be multi-coloured, so that the lamp can show many colours ofchoice. Although the figures show a circle shape of the arrays, othershapes like a rectangular shape are also possible. The central part 40Aof the lamp comprises a plastic lens 41 in front of the LEDs 21 forfocussing the central light beam. An intermediate part 40B comprises aring of LEDs without a lens. The LEDs in the central and intermediateparts 40A/B are arranged such that their axes of their light beams areparallel with the lamp axis. In the third part 40C the LEDs 21 aremounted at a angle with the lamp axis, which angle is between 0 and 90degrees, for instance 40 degrees. The LEDs are mounted such, that at apredefined minimum use distance from the lamp (for instance 1 m) away,the light beams of each LED overlaps with its neighbour's, such that acontinuously lighted area is obtained.

The LEDs are mounted in a metal housing having walls separating thethree groups of LEDs, and which performs a heatsink function for coolingpurposes.

With reference to FIG. 23 a gesture light control system as describedabove (or alternatively an ordinary Remote Control) sends light beamposition or focus instructions to a micro-controller 40. Themicro-controller 41 translates this information into instructions as towhich LEDs 21 have to be selected and as to the intensity of each of theLEDs 21. An expander/selector 42 is used for selecting the large amountof drivers 43 and the LEDs 21 connected thereto.

For a point light source the relationship between the perceivedbrightness B and the measured illuminance E is:

B=k·{square root over (E)}

which is a non-linear behaviour that has to be compensated. If theaverage perceived brightness is to be kept constant during control ofthe light beam than the average illumination E has to be constant.Therefore the total luminous flux incident on a surface per unit area iskept constant during control of the light beam.

FIGS. 24A-24G schematically shows how the direction of the combinedlight beam in the lamp of FIG. 22 is smoothly changed from a downwarddirection in FIG. 24A to a laterally slanting direction in FIG. 24G(lighter hatched areas represent lighter areas/LEDs, more denselyhatched areas represent darker areas/LEDs). For carrying out thiscontrol instruction the micro-controller in the lamp is arranged togradually change the brightness of individual LEDs such that theimpression of said smooth change in direction of the combined light beamis obtained.

FIGS. 25A-25E schematically shows how the angle of the combined lightbeam in the lamp of FIG. 22 is smoothly changed from a broad beam havinga large angle in FIG. 25A to a focussed beam having a small angle inFIG. 24E. For carrying out this control instruction the micro-controllerin the lamp is arranged to gradually change the brightness of individualLEDs such that the impression of said smooth change in angle of thecombined light beam is obtained.

Although the invention is described herein by way of preferredembodiments as example, the man skilled in the art will appreciate thatmany modifications and variations are possible within the scope of theinvention.

1. A lighting system comprising: a lamp arranged to transformelectricity into a light beam having properties such as intensity,colour, colour temperature, direction and beam cone angle; a lightcontrol means arranged to adjust said light beam properties; anultrasonic transmitter arranged to transmit ultrasonic signals; anultrasonic receiver arranged to receive reflected ultrasonic signals;wherein said ultrasonic transmitter and/or receiver are mounted on arotatable carrier such that the beam of said transmitter and/or thereception cone of said receiver extend parallel to and at a distancefrom the axis of rotation, wherein driving means are present to rotatesaid carrier; and a processing means arranged to send an ultrasonicpulse repeatedly through said transmitter during rotation at a multitudeof angular positions of said carrier and to determine after each pulseis sent if said receiver receives a reflected ultrasonic signal with anamplitude exceeding a predetermined threshold within a predeterminedperiod, and to send control signals to said light control means independence of said determination.
 2. The lighting system of claim 1,wherein the axis of rotation of said rotatable carrier extends within,and parallel to, the light beam of the lamp.
 3. The lighting system ofclaim 1, wherein said processing means is arranged to send an ultrasonicpulse at least 3, preferably at least 6, more preferably at least 12angular positions of said carrier.
 4. The lighting system of claim 1,wherein said transmitter and receiver is a combined transceiver.
 5. Thelighting system of claim 1, wherein said receiver is provided with asound horn.
 6. The lighting system of claim 1, wherein the processingmeans is arranged to select in dependence of said determination a typeof control signals from a plurality of types of control signals, whereineach type of control signals controls a different one of said lightproperties.
 7. The lighting system of claim 1, wherein said processingmeans are further arranged to derive a time-of-flight signalrepresenting the time differences between said transmitted and receivedultrasonic signals and to send control signals to said light controlmeans in dependence of said time-of-flight signal.